F.D.A. Asks Pediatricians to Stop Using a Diarrhea Vaccine for Now

By GARDINER HARRIS

Published: March 23, 2010

WASHINGTON -- Federal drug regulators on Monday asked the nation's pediatricians to stop giving children a diarrhea vaccine until federal scientists can figure out why the product contains apparently harmless but extraneous pieces of a pig virus.

The vaccine, called Rotarix, is manufactured by GlaxoSmithKline and is intended to prevent severe cases of rotavirus infections, a diarrheal illness that can cause dehydration in infants and young children.

''This was a difficult decision for us because there is no evidence at this time that there is a risk to children,'' said Dr. Margaret Hamburg, the Food and Drug Administration commissioner.

For now, the decision is unlikely to disrupt routine immunizations in children since a second vaccine, this one made by Merck and called RotaTeq, remains available. RotaTeq was approved for use in the United States in 2006 and is still the more popular vaccine. Rotarix was approved in 2008 and has been used to vaccinate about one million children.

The vaccines are usually provided by mouth to children at two and three months of age.

Neither doctors nor parents need worry about potential illnesses in children who were vaccinated with Rotarix, Dr. Hamburg said, because the viral particles have been present in the vaccine from the earliest stages of its development. Extensive testing before and after approval has shown the vaccine to be safe, she said. Using a novel laboratory technique, academic researchers recently tested a variety of vaccines and found the extraneous viral components only in Rotarix.

''We're not taking this vaccine off the market,'' Dr. Hamburg said. ''We're simply asking that there be a pause in its use.''

Thomas Breuer, chief medical officer of GlaxoSmithKline Biologicals, said, ''No safety issue has been identified by external agencies or GSK.'' The company said it would continue producing the vaccine with the extraneous virus, which originated in pigs, until it could figure out a way to fix the process. A committee of independent experts will be impaneled in the next four to six weeks to advise the F.D.A. on how to proceed with Rotarix.

The agency's decision to push for a pause in the vaccine's use even when it has not been found to harm anyone is likely to send a shiver through the biotechnology industry, which produces highly complex medicines through biological manufacturing processes that can yield sometimes unpredictable outcomes.

The decision also demonstrates that lawyers have lost considerable power at the F.D.A. since Dr. Hamburg was made commissioner. Neither statutes nor agency rules allow the commissioner to ask doctors to pause in their use of a medical product because the agency does not regulate the practice of medicine. In the past, commissioners -- on the strong advice of agency lawyers -- generally restricted their actions to those for which Congress has given explicit authority.

But that approach ignored the extraordinary power of agency commissioners to affect public health simply through announcements, and Dr. Hamburg demonstrated Monday that she would not be as cautious. ''It is important to have a little more flexibility in our regulatory approach,'' Dr. Hamburg said.

Vaccines for rotavirus have a difficult history. The first such vaccine, called RotaShield, was approved for use in the United States in 1998 and withdrawn a year later after it was linked with rare cases of intussusception, or bowel obstruction.

Before widespread vaccinations, rotavirus infections in the United States caused 50,000 hospitalizations annually but only a few dozen deaths. Adequate medical care almost always saves dehydrated children. In the developing world, an estimated 500,000 children die each year from poorly treated rotavirus infections.

''In many countries, rotavirus causes so much severe illness and death that the known benefits of continued use of Rotarix far outweigh any theoretical risk of harm from the vaccine,'' Dr. Thomas R. Frieden, director of the Centers for Disease Control and Prevention, said in a written statement.